Corona Discharge Devices are used to treat the surface of various materials such as polyethylene film by passing the film between a pair of electrodes. Generally one of the electrodes comprises a metallic roll which is used to carry the film through the discharge zone and a segmented electrode assembly pivotally mounted for movement between an operative position spaced from the rod electrode and an inoperative position for maintenance or repair. The electrode assembly includes a plurality of electrode segments having square metallic electrodes mounted on a common base with a hollow ceramic or insulating member mounted on the end of each of the electrodes. The electrode segments are offset one from the other to provide a corona discharge across the entire surface of the film. One of the problems with this type of a corona discharge device is the production of striping on the film due to the uneven exposure of the film to the corona discharge field produced by the square segments. Cooling of the segments has also been a problem since the highest temperature occurs in the corona discharge field or zone between the two electrodes. Finally, the spacing in the gap between the electrodes is difficult to control because of the variations in thickness of the ceramic members.